This application is the national phase under 35 U.S.C. xc2xa7371 of PCT International Application No. PCT/JP98/05924 which has an International filing date of Dec. 24, 1998, which designated the United States of America.
The present invention relates to a gas-liquid separator for separating gas and liquid in gas-liquid two-phase fluid, i.e. gas containing liquid suspended therein, generated in an air conditioner, clothes dryer, internal-combustion engine, or the like, and more particularly to a vortex-stream gas-liquid separator for separating air and water in the fluid circulated in a clothes dryer by passing a circularly whirling vortex stream through the fluid passage inside the drying chamber of the clothes dryer.
Vortex-stream gas-liquid separators are used in various fields as a simple mechanism for separating gas and liquid in gas-liquid two-phase fluid. For example, Japanese Laid-Open Patent Application No. H5-38408 discloses a vortex-stream gas-liquid separator for removing moisture from the steam used in a geothermal power plant, and Japanese Laid-Open Patent Application No. H5-86831 discloses a vortex-stream gas-liquid separator for separating mist of lubricating oil from the blow-by gas generated in an internal-combustion engine.
FIGS. 1A and 1B show the vortex-stream gas-liquid separator disclosed in Japanese Laid-Open Patent Application No. H5-38408 mentioned above. FIG. 1A shows a vertical sectional view of the vortex-stream gas-liquid separator 9, and FIG. 1B shows a horizontal sectional view thereof taken along the line Axe2x80x94A shown in FIG. 1A. This vortex-stream gas-liquid separator 9 is composed of a casing 10 having a fluid passage 1 having a cylindrical cross section, a fluid inlet 2 for introducing gas-liquid two-phase fluid, a gas outlet 3, and a liquid outlet 5.
The casing 10 is arranged vertically with the axis of the fluid passage 1 lying vertically. The fluid inlet 2 is provided substantially at the center, in the vertical direction, of the casing 10 in such a way as to introduce the gas-liquid two-phase fluid in the direction of a line tangential to the circular cross section of the fluid passage 1. The gas outlet 3 is provided so as to be coaxial with the fluid passage 1 by being inserted into the casing 10 from below in such a way that an opening of the gas outlet 3 is located in an upper portion of the inside of the casing 10. The liquid outlet 5 is provided in a lower portion of the casing 10.
The gas-liquid two-phase fluid introduced through the fluid inlet 2 into the casing 10 collides with the inner wall of the casing 10 as it passes through the fluid passage 1 in the form of a vortex stream. As a result of this collision, the droplets of the liquid contained in the gas-liquid two-phase fluid are condensed on the wall surface, then flow downward along the wall surface, and are eventually discharged through the liquid outlet 5. On the other hand, the gas that remains after the removal of the droplets of the liquid is discharged through the opening 3a of the gas outlet 3.
FIGS. 2A, 2B, and 2C show the vortex-stream gas-liquid separator disclosed in Japanese Laid-Open Patent Application No. H5-86831 mentioned above. FIG. 2A is a front view of the vortex-stream gas-liquid separator 9, FIG. 2B is a side view thereof as seen from the direction B shown in FIG. 2A, and FIG. 2C is a horizontal sectional view thereof taken along the line Axe2x80x94A shown in FIG. 2A. This vortex-stream gas-liquid separator 9 is composed of a casing 10 having a cylindrical cross section and having a fluid passage 1, a fluid inlet 2 for introducing gas-liquid two-phase fluid, a gas outlet 3, and a liquid collection reservoir 7 provided below the fluid passage 1.
The casing 10 is arranged horizontally with the axis of the fluid passage 1 lying horizontally. The fluid inlet 2 is provided at one end of the casing 10 in such a way as to introduce the gas-liquid two-phase fluid in the direction of a line tangential to the circular cross section of the fluid passage 1. The gas outlet 3 is provided so as to be coaxial with the fluid passage 1 by being inserted into the casing 10 from that end 1a of the casing 10 at which the fluid inlet 2 is provided in such a way that an opening 3a of the gas outlet 3 is located near the other end 1c of the casing 10 opposite to the fluid inlet 2. Between the fluid passage 1 and the liquid collection reservoir 7 is provided a partition wall having slits 11 formed therein. The liquid collection reservoir 7 is provided with an outlet 8 for discharging the collected liquid.
The gas-liquid two-phase fluid introduced through the fluid inlet 2 into the fluid passage 1 forms a vortex stream that whirls circularly (in the direction indicated by an arrow J) along the inner wall of the casing 10 as it passes through the fluid passage 1 in the direction indicated by an arrow K. Meanwhile, the droplets of the liquid contained in the gas-liquid two-phase fluid collide with and are condensed on the inner wall of the casing 10, then flow downward along the wall surface, and then drip through the slits 11 into the liquid collection reservoir 7. The liquid collected in the liquid collection reservoir 7 is discharged through the liquid outlet 8. While the droplets of the liquid are being removed in this way, the gas-liquid two-phase fluid advances horizontally until it reaches the opening 3a of the gas outlet 3, through which the gas that remains after the removal of the droplets of the liquid is discharged.
In the vertical-type vortex-stream gas-liquid separator shown in FIGS. 1A and 1B, making the gas-liquid separator as a whole more compact requires making the fluid passage narrower. Thus, to treat the same amount of gas-liquid two-phase fluid, the fluid needs to be passed at an increased flow rate. However, as the flow rate increases, the droplets of the liquid that have condensed on the inner wall of the casing 10 increasingly tend to flow toward the opening 3a of the gas outlet 3 rather than flowing downward. This leads to lower gas-liquid separation performance. In other words, it is difficult to make this vertical-type vortex-stream gas-liquid separator more compact without sacrificing the gas-liquid separation performance.
On the other hand, in the horizontal-type vortex-stream gas-liquid separator shown in FIGS. 2A, 2B, and 2C, the gas-liquid two-phase fluid is allowed to flow freely through the slits 11 into the liquid collection reservoir 7, and thus comes to contain again the droplets of the liquid that have once been separated. Accordingly, the gas discharged through the gas outlet 3 contains a large number of droplets of the liquid. This leads to unsatisfactory gas-liquid separation performance. Moreover, since the fluid inlet 2 and the gas outlet 3 are provided at the same end of the casing 10, discharging the gas requires reversing the flow direction of the gas inside the fluid passage 1. This causes pressure loss.
An object of the present invention is to provide a compact vortex-stream gas-liquid separator that offers high gas-liquid separation performance with minimal pressure loss, and to provide a gas-liquid separation system employing such a gas-liquid separator.
To achieve the above object, according to one aspect of the present invention, a vortex-stream gas-liquid separator for separating gas and liquid contained in gas-liquid two-phase fluid is provided with a fluid passage having substantially the shape of a column and arranged with the center axis thereof lying substantially horizontally, a fluid inlet provided near a first end surface of the fluid passage so as to introduce the gas-liquid two-phase fluid into the fluid passage in such a way that the gas-liquid two-phase fluid passes through the fluid passage in the form of a vortex stream, a gas outlet provided at a second end surface of the fluid passage substantially coaxially with the fluid passage so as to discharge separated gas, and a liquid outlet provided in a lower portion of the fluid passage between the center and the second end surface of the fluid passage so as to discharge separated liquid.
The gas-liquid two-phase fluid introduced through the fluid inlet provided near the first end surface into the fluid passage collides with the wall surface that defines the circumferential surface of the substantially columnar fluid passage as it passes toward the second end surface in the form of a vortex stream. As a result of this collision, the liquid contained in the gas-liquid two-phase fluid clings to the wall surface as droplets, and is thereby separated from the gas. Under the influence of gravity and the flow of the gas-liquid two-phase fluid, the droplets of the liquid that have condensed on the wall surface reach the liquid outlet, and are discharged therethrough out of the fluid passage. The gas thus separated from the liquid reaches the second end surface, and is discharged through the gas outlet provided there out of the fluid passage.
The liquid outlet is provided between the center and the second end surface of the fluid passage, and therefore the gas-liquid two-phase fluid that has been introduced through the fluid inlet into the fluid passage is not influenced by the liquid outlet until it reaches the center of the fluid passage. Accordingly, the vortex stream of the gas-liquid two-phase fluid is maintained stably while it passes through a sufficiently long distance, and meanwhile sufficient separation of the gas and the liquid is achieved. This helps achieve high separation performance. Moreover, the fluid inlet and the gas outlet are provided at one end and at the other end, respectively, of the fluid passage, and therefore the flow direction of the gas-liquid two-phase fluid does not need to be reversed inside the fluid passage. This helps minimize pressure loss.
This vortex-stream gas-liquid separator has a very simple structure, and can thus be made more compact easily. Moreover, this vortex-stream gas-liquid separator has no member provided inside the fluid passage, and therefore, even if it is made more compact, the cross-sectional area of its fluid passage is not reduced to a larger extent than is inevitable to make the gas-liquid separator as whole more compact. Thus, it is possible to realize a vortex-stream gas-liquid separator that is compact but nevertheless offers high gas-liquid separation performance.
This vortex-stream gas-liquid separator may be further provided with a liquid collection reservoir arranged below the fluid passage and communicating with the fluid passage through the liquid outlet so as to collect the liquid discharged through the liquid outlet. This helps prevent the separated liquid from moistening the surroundings of the vortex-stream gas-liquid separator, and thereby alleviates the restrictions as to where to install and use the vortex-stream gas-liquid separator. Moreover, the gas is discharged only through the gas outlet, and therefore it is possible to introduce the gas-liquid two-phase fluid into the fluid passage not only by blowing it in through the fluid inlet but also by sucking it out through the gas outlet. This helps widen the application of the vortex-stream gas-liquid separator.
Furthermore, the liquid outlet is provided not over the entire length of the fluid passage but between the center and the second end surface of the fluid passage. This makes it difficult for the gas-liquid two-phase fluid to flow into the liquid collection reservoir, and thus makes it difficult for the liquid collected in the liquid collection reservoir to be contained again in the gas-liquid two-phase fluid. This helps maintain high gas-liquid separation performance.
To prevent the gas-liquid two-phase fluid having flown into the liquid collection reservoir from blowing up the liquid collected in the liquid collection reservoir, it is preferable that the liquid collection reservoir be so shaped and sized that, when a predetermined amount of the liquid is collected therein, the surface of the collected liquid is 10 mm or more away from the liquid outlet.
It is possible to provide additionally, in a lower portion of the liquid collection reservoir, a drain outlet and, inside the liquid collection reservoir, a float that floats on the liquid collected in the liquid collection reservoir and a valve that is coupled to the float so as to open/close the drain outlet by moving together with the float. This makes it possible to discharge automatically the liquid collected in the liquid collection reservoir when it reaches a predetermined level.
It is preferable that the float and the valve be so designed as to keep the surface of the collected liquid 10 mm or more away from the liquid outlet at all times. This helps prevent the gas-liquid two-phase fluid having flown into the liquid collection reservoir from blowing up the liquid collected in the liquid collection reservoir, and thereby maintain high gas-liquid separation performance at all times.
It is preferable that the fluid inlet introduce the gas-liquid two-phase fluid in such a way that the gas-liquid two-phase fluid flows into only one of the two portions of the fluid passage divided by a plane including the center axis of the fluid passage and substantially parallel to that plane. This makes it difficult for the gas-liquid two-phase fluid passing through the fluid passage in the form of a vortex stream to include a component that whirls in the direction opposite to the vortex stream. This helps stabilize the vortex stream of the gas-liquid two-phase fluid, and thereby achieve high separation performance.
To achieve higher gas-liquid separation performance, it is preferable that the liquid outlet reach the second end surface of the fluid passage.
It is possible to provide additionally a damming means near the liquid outlet so as to prevent the liquid that has condensed on the inner circumferential surface of the fluid passage from traveling toward the second end surface of the fluid passage.
It is possible to provide additionally a restricting means on the second end surface of the fluid passage so as to prevent the liquid from flowing along the second end surface to the gas outlet. For example, the restricting means is realized as a pipe that at one end communicates with the gas outlet and that at the other end protrudes inward from the second end surface of the fluid passage so as to have an opening inside the fluid passage. To achieve even higher gas-liquid separation performance, it is possible to provide additionally a partition plate that extends from the end of the pipe radially outward inside the fluid passage, with at least two thirds of the liquid outlet located between the partition plate and the second end surface of the fluid passage.
It is preferable that the liquid outlet measure 8 mm or more and 30 mm or less along the center axis of the fluid passage. Making the liquid outlet so small helps make it more difficult for the gas-liquid two-phase fluid to flow into the liquid collection reservoir, and thereby achieve higher gas-liquid separation performance.
Providing a plurality of liquid outlets within an area measuring 8 mm or more and 30 mm or less along the center axis of the fluid passage serves the same purpose.
It is possible to give resilience to the wall surface of the member that defines the circumferential surface of the fluid passage. This helps prevent the liquid contained in the gas-liquid two-phase fluid that has collided with the wall surface from being splashed and contained again in the gas-liquid two-phase fluid, and thereby achieve still higher separation performance.
To achieve the above object, according to another aspect of the present invention, a vortex-stream gas-liquid separator for separating gas and liquid contained in gas-liquid two-phase fluid is provided with a fluid passage having substantially the shape of a columnar and arranged with the center axis thereof lying substantially horizontally, a fluid inlet provided near a first end surface of the fluid passage so as to introduce the gas-liquid two-phase fluid into the fluid passage in such a way that the gas-liquid two-phase fluid passes through the fluid passage in the form of a vortex stream, a gas outlet provided at a second end surface of the fluid passage substantially coaxially with the fluid passage so as to discharge separated gas, a liquid outlet provided in a lower portion of the fluid passage about half a turn or more away from the fluid inlet in the direction of the vortex stream of the gas-liquid two-phase fluid and having a strip-like shape extending along the center axis of the fluid passage, and a liquid collection reservoir provided below the fluid passage and communicating with the fluid passage through the liquid outlet so as to collect the liquid discharged through the liquid outlet.
In this vortex-stream gas-liquid separator, the liquid collection reservoir that communicates with the fluid passage through the liquid outlet is provided below the fluid passage. The liquid outlet has a rectangular shape that is longer along the center axis of the fluid passage, and is thus shorter in width. This makes it difficult for the gas-liquid two-phase fluid passing through the fluid passage in the form of a vortex stream to flow into the liquid collection reservoir. Moreover, the liquid outlet is provided approximately about half a turn or more away from the fluid inlet in the direction of the vortex stream of the fluid, and therefore it little influences the gas-liquid two-phase fluid that has just entered the fluid passage. This helps maintain the vortex stream of the gas-liquid two-phase fluid stably, and thereby achieve high gas-liquid separation performance. Moreover, the fluid inlet and the gas outlet are provided at one end and at the other end, respectively, of the fluid passage, and therefore the flow direction of the gas-liquid two-phase fluid does not need to be reversed inside the fluid passage. This helps minimize pressure loss.
To achieve the above object, according to still another aspect of the present invention, a gas-liquid separation system is provided with a vortex-stream gas-liquid separator as described above, a compressor for compressing air, a heat exchanger for exchanging heat between air fed from the compressor and air fed from the gas outlet of the vortex-stream gas-liquid separator, and an expander for expanding the air fed from the compressor through the heat exchanger and then feeding the thus expanded air to the fluid inlet of the vortex-stream gas-liquid separator.
In this gas-liquid separation system, air in a first, high-humidity, state is converted into air in a second, high-temperature and high-humidity, state by the compressor, then the air in the second state is converted into air in a third, low-temperature and high-humidity, state by the heat exchanger, then the air in the third state is converted into air in a fourth, low-temperature, high-humidity, and water-droplets-containing, state by the expander, then the air in the fourth state is separated into water and air in a fifth, low-temperature, high-humidity, and water-droplets-free, state by the vortex-stream gas-liquid separator, and then the air in the fifth state is converted into air in a sixth, high-temperature and low-humidity, state by the heat exchanger.
Since the vortex-stream gas-liquid separator described above offers high separation performance with minimal pressure loss, this gas-liquid separation system employing it is highly efficient. Moreover, heat is exchanged between the air before gas-liquid separation and the air after gas-liquid separation so as to raise the temperature of the latter greatly. Thus, this gas-liquid separation system is suitable for a clothes dryer or the like.